Add function-docstring for app init

app/__init__.py

@@ -20,6 +20,15 @@ import rc_util  # noqa: E402
 
 
 def create_app(config_name):
+    """
+    Create main flask app
+
+    input:
+        config_name: environment of the app running
+    output:
+        Flask instance
+    """
+
     app = Flask(
         __name__, static_folder="static"
     )  # initialization of the flask app